CPO Disinfection Systems & Sanitization Methods 2

Question 1

How does ultraviolet (UV) disinfection work in pool water treatment systems?

Accepted Answer

UV light penetrates microorganisms and disrupts their DNA, preventing reproduction

Answer

UV systems expose water to ultraviolet light at a specific wavelength (typically 254 nm) that damages microbial DNA, inactivating pathogens without adding chemicals, though a residual sanitizer is still required.

Question 2

What is a key limitation of ozone (O₃) as the sole pool sanitizer?

Accepted Answer

Ozone provides no residual disinfectant in the pool water after treatment

Answer

Ozone is a powerful oxidizer that destroys contaminants in the treatment chamber, but it rapidly dissipates and provides no measurable residual disinfection in the pool water, so a secondary sanitizer like chlorine is always required.

Question 3

A saltwater chlorination system (electrolytic chlorine generator) produces chlorine by which process?

Accepted Answer

Passing an electrical current through sodium chloride (salt) solution to generate hypochlorous acid

Answer

An electrolytic chlorine generator (ECG/SWG) passes electricity through a dilute salt solution across titanium electrodes, splitting NaCl into sodium hypochlorite and hypochlorous acid — effective chlorine.

Question 4

What is the function of cyanuric acid (CYA) in an outdoor pool?

Accepted Answer

It acts as a chlorine stabilizer, reducing UV degradation of free chlorine by sunlight

Answer

Cyanuric acid bonds loosely with chlorine, shielding it from ultraviolet light degradation and significantly extending the effective life of free chlorine in outdoor pools.

Question 5

At what cyanuric acid (CYA) level does pool health guidance generally indicate that chlorine effectiveness becomes significantly compromised, requiring dilution or draining?

Accepted Answer

Above 100 ppm

Answer

Most health guidelines and the Model Aquatic Health Code (MAHC) recommend maximum CYA levels of 100 ppm, beyond which chlorine is so tightly bound that it cannot effectively inactivate pathogens in reasonable time.

(CPO) Certified Pool and Spa Operator Practice Test

(CPO) Certified Pool and Spa Operator Practice Test

CPO Disinfection Systems & Sanitization Methods 2